Having said that, A solution to any problem must address all issues, technical and social. Reiserfs v3 and v4 are unfortunately marginalised by
1) (above quote)
2) Hans' no-nonsense attitude to various people
3) Hans' legal problem
4) reiserfsck tree splicing bug.
5) Reiser4's non-inclusion in kernel due to (2) (3).
As for Ext3/4, I can't comment personally as my few experiences of ext3 were so sluggish i've hardly used it.... But i suspect energyman is right ( ;> ).